How to format trackball tooltip text in ejChart?

By default, trackball displays the “x” value and “y” value of a point as tooltip text when you move the mouse over the Chart area. The “x” value in trackball tooltip text is formatted based on the LabelFormat property of the Horizontal axis used by the series and the “y” valuedisplayed in trackball tooltip text is formatted based on the LabelFormat property of the Vertical axis used by the series.